From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964962AbWFZLUX (ORCPT ); Mon, 26 Jun 2006 07:20:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964997AbWFZLUX (ORCPT ); Mon, 26 Jun 2006 07:20:23 -0400 Received: from mtagate1.de.ibm.com ([195.212.29.150]:17503 "EHLO mtagate1.de.ibm.com") by vger.kernel.org with ESMTP id S964962AbWFZLUX (ORCPT ); Mon, 26 Jun 2006 07:20:23 -0400 Date: Mon, 26 Jun 2006 13:19:38 +0200 From: Heiko Carstens To: Mike Grundy Cc: Jan Glauber , Martin Schwidefsky , linux-kernel@vger.kernel.org, dwilder@us.ibm.com Subject: Re: [PATCH] kprobes for s390 architecture Message-ID: <20060626111938.GC9418@osiris.boeblingen.de.ibm.com> References: <20060626080910.GA9418@osiris.boeblingen.de.ibm.com> <20060626104945.GA1244@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060626104945.GA1244@localhost.localdomain> User-Agent: mutt-ng/devel-r804 (Linux) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 26, 2006 at 03:49:45AM -0700, Mike Grundy wrote: > On Mon, Jun 26, 2006 at 10:09:10AM +0200, Heiko Carstens wrote: > > > After reading your notes it's probably overkill doing the cs on each cpu, since > > > the interrupt will discard the prefetched instructions. > > > > Indeed. Another thing that should not be forgotten: it could be that the > > whole kernel text segment resides in a shared read only segment. So it can > > be shared by multiple z/VM guests. > > In that case the cs instruction will fail. Looks like you need to write the > > part that replaces the instruction in assembly and supply a fixup section > > which in turn makes sure that -EFAULT is returned. > > If it fails, won't it will generate a program interrupt, 5 (access exception)? Yes, that's why you need a fixup section :)